I have a 1964 riv that has an RPM specific vibration. When I first cranked it I thought it has to be something in the flywheel or torque converter. I have pulled the motor and the only thing I can find is the flywheel may not have been lined up with the crank. Would this be true? What else could be vibrating like that? By the way, this is all while the car is parked.
That would do it. The flywheel will line up 6 ways. but is only balanced when the alignment hole in the crank and flywheel are centered over one another. Cheryl
Could this also cause a vibration in the driveline? One of the reasons my car came all apart was a vibration between 55-65 mph. I totally destroyed two sets of axle and carrier bearings due to this vibration, the driveshaft was also replaced. I neglected to look and see if the flywheel was lined up when I disassembled the engine, so I can't say if that was it. Mark
I had a 264" nailhead in my '55 Special which would vibrate at 63 mph exactly! It would cruise all day at 62, but hit 63 and the vibration would start and get worse as the speed increased. Turned out that, when the engine was rebuilt for the guy I bought the car from, it wasn't balanced correctly. Apparently Buick nailheads are an internally balanced engine (all engine components are balanced together as a single unit), while most other engines are externally balanced (each piece individually balanced). Most engine builders, not being familar with nailheads, assume it's externally balanced like a SBC. Anyway, I had it rebalanced externally and the vibration went away. Later, I built & installed a 401" in the car and had it externally balanced and never have had any vibration from it. Maybe some others more knowledgable than I can comment on balancing. Sometimes I know just enough to be dangerous !!
Internal- External Internally balanced engines are just that: a rotating assembly balanced using only the internal parts (crank, rods, pistons). The flywheel/flexplate and vibration dapener are balanced neutral (without more weight in any radial direction from the center of the crank) in the internally balanced engine. The externally balanced engine uses a weighted vibration dampener and flywheel/flexplate in combination with the internal parts to balance the rotating assembly. The dampener and flyywheel/flexplate have more weight in one section that offsets weight in the internal parts. Internally balanced engines are generally more expensive to manufacture since it is easier to add more weight to a vibration dampener or flexplate/flywheel then it is to add it across the crankshaft. The Nailhead and BBB are externally balanced. Many excellent race motors are externally balanced, but the best of the best are usually internally balanced. Mark, you would feel the vibration in the driveline, but it would also be in all gears through the same rpm range. It would just seem less intense in the lower gears as you go through the rpm range quicker in the lower gears. It would also do it in park or neutral through the same rpm range as it does when you are driving. That is how I finally figured out it was not the driveline in mine. Cheryl
Cheryl, Thanks for the info. The vibration was only felt at highway speeds, not as you ran through the gears. At least thats what I recall, as I haven't driven it in ten years. Before I bought the car, the clutch, pressure plate, driveshaft and u-joints were all replaced and the vib was still there. The trans was gone through and checked as well. I drove the car to Bonneville and back, and all the rear axle bearings with the exception of the pinion were gone. That was about a 3000 mile trip. I guess I'll find out when this thing is back together. With all the driveline items gone through as I stated, my guess it was either the flywheel or the harmonic balancer, which had rubber chunks missing and could have part of the problem. Mark
Vibration at 65 MPH/2500 RPM Guys, I am having the same problem. At 65 mph / 2500 rpm my car has a serious vibration. I lined up the hole on the crank in january when I installed the motor. I pretty much know it isn't the motor though since my my car had the same problem with the old motor. I had a bad drive shaft, and replaced it a couple months ago. Would a bad rear end do the same thing? I had the bad drive shaft for many years. since this car has had this problem for 10 or more years I gave up trying to find it but I have to drive the freeway every day to get to and from work. The only thing I haven't done is rebuild the rear end. I even have new wheels and tires. I am a bit frustrated. BTW it doesn't do it at all when I am lighting up the rear tires. Any help would be greatly appreciated.
Sounds like we need to start a support group for people with this problem. I rebuilt my engine after noticing a similar vibration, mine is from 1750 to around 2000 rpm, most noticable when decelerating in top gear. It is apparent when the car is in neutral, on both accell and decell, but as stated, most aggressive in third gear. I have had the rearend rebuilt, drive shaft balanced three times, pinion angle checked and modified, rebuilt and balanced (internally) the engine and still, the vibration persists. Also tried three different harmonic balancers, no change. Very, very distressing. The car runs well in all other respects, it just vibrates in this one area. I am putting on an x-pipe to try and rule out header vibration, which the engine builder suspects it is coming from. If that isn't the source, then: Questions: What damage is being done, if any? What the hell is it? What if anything can be done to fix it? I love my car, its just that I am so close to having it right where I want it, I want this issue resolved.
The vibration during de-celleration is most likely due to a worn out tailshaft bushing in the transmission. A vibration during acceleration/load is caused by a problem at the rear of the driveshaft/pinion yoke, and a vibration during decelleration is caused by a problem at the front end of the driveshaft. My '65 special had the problem during deceleration, so I replaced the tailshaft bushing in the transmission and it went away. The way to check is to grab the driveshaft with your hand and try to move it up and down to check the slop where it sticks into the back of the transmission. Should be just a very slight amount of movement there. If it moves up and down 1/8" or more, the bushing in the tail of the transmission is worn out.
I took my car to a reputable transmission repair shop, who gave it a clean bill of health. I would take it to another, but my vibration is in the same rpm range when in neutral, park or in gear. If the trans is the culprit, would it still vibrate, whether it is in gear or not. If so, back to the trans shop it goes. Thanks for the help.
If the vibration is the same under load, in park, etc., I would bet that it is in the engine because the transmission, drive line, and rear end are not in motion under all of the above. Did the vibration start suddenly? Was it there from the beginning? If it started suddenly, check the balancer and like rotating components on the engine. If it was there all along, check the alignment of the balancing alignment hole in the back of the crank. I sure hope this helps you out.
